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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'bf76c0efe8e1df38c63a39bbe8a419e063d5e8d04b788755d0bf43c1ee366d59' 
  AND token = 'M09tYuuIor6KrRTk9vwuVjSZQOBF0gTVcSfWHbsgBUQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}